Wafer defect inspection apparatus and method for inspecting a wafer defect

Abstract

It is judged whether or not an average gray level of an image of a wafer W that is an inspection target and that has been imaged by the light receiving part 2 is in the defect detectable range. A control processing part 6 a is configured to modify an exposure time in imaging the wafer W and to obtain an image of the wafer W again by the light receiving part 2 in the case in which it is decided that an average gray level of an image of the wafer W is not in a defect detectable range, and an image processing part 6 b is configured to carry out a defect inspection based on an image of the wafer W in the case in which it is decided that an average gray level of the image of the wafer W is in the defect detectable range.

What is claimed is: 
     
       1. A wafer defect inspection apparatus comprising:
 a wafer mounting means configured to mount a wafer that is an inspection target; 
 an irradiation means configured to irradiate the wafer with an infrared light; 
 an imaging means configured to image the wafer that has been irradiated with the infrared light; 
 an inspection means configured to inspect a defect of the wafer based on an image of the wafer that has been imaged by the imaging means; 
 a gray level judgment means configured to judge whether or not a reference gray level of an image of the wafer that is the inspection target and that has been imaged by the imaging means is in a predetermined gray level range; and 
 a control means configured to 
 modify an exposure time by changing an image capture rate of the imaging means and modifying a relative velocity of the irradiation means and the imaging means to the wafer mounting means in imaging the wafer and to obtain an image of the wafer again by the imaging means in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range, wherein the inspection means is configured to carry out a defect inspection based on an image of the wafer in the case in which it is decided that a reference gray level of the image of the wafer is in the predetermined gray level range. 
 
     
     
       2. The wafer defect inspection apparatus according to  claim 1 , wherein:
 the irradiation means is configured to irradiate the wafer with the infrared light in a line pattern, 
 the imaging means is an image line sensor, and 
 the control means is further configured to obtain an image of the entire wafer by relatively moving the irradiation means, the imaging means, and the wafer mounting means. 
 
     
     
       3. The wafer defect inspection apparatus according to  claim 2 , wherein the irradiation means and the imaging means are disposed on the opposite sides from each other across the wafer mounted on the wafer mounting means. 
     
     
       4. The wafer defect inspection apparatus according to  claim 1 , wherein the control means is further configured to:
 adjust at least one of an intensity of the infrared light of the irradiation means or a photodetective sensitivity of the imaging means and to obtain an image of the wafer again in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range; and 
 modify the exposure time in the case in which the gray level is not in the predetermined gray level range even if the intensity of the infrared light and the photodetective sensitivity of the imaging means are adjusted. 
 
     
     
       5. A method for inspecting a wafer defect comprising:
 irradiating a wafer that is an inspection target with an infrared light by an irradiator, the wafer mounted on a wafer mount, and imaging, via a light receiver, the wafer that has been irradiated with the infrared light; 
 judging whether or not a reference gray level of an image of the wafer that is the inspection target and that has been imaged is in a predetermined gray level range; 
 modifying an exposure time by changing an image capture rate of the light receiver and modifying a relative velocity of the irradiator and the light receiver to the wafer mount in imaging the wafer and obtaining an image of the wafer again in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range; and 
 carrying out a defect inspection of the wafer based on an image of the wafer in the case in which it is decided that a reference gray level of the image of the wafer is in the predetermined gray level range. 
 
     
     
       6. A wafer defect inspection apparatus comprising:
 a wafer mount configured to mount a wafer that is an inspection target; 
 an irradiator configured to irradiate the wafer with an infrared light; 
 a light receiver configured to image the wafer that has been irradiated with the infrared light;
 a processor; and 
 a memory that stores an instruction, the apparatus further comprising, as a configuration when the processor executes the instruction stored in the memory:
 an inspector configured to inspect a defect of the wafer based on an image of the wafer that has been imaged by the light receiver; 
 a gray level judger configured to judge whether or not a reference gray level of an image of the wafer that is the inspection target and that has been imaged by the light receiver is in a predetermined gray level range; and 
 a controller configured to
 modify an exposure time by changing an image capture rate of the light receiver and modifying a relative velocity of the irradiator and the light receiver to the wafer mount in imaging the wafer and to obtain an image of the wafer again by the light receiver in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range, wherein the inspector is configured to carry out a defect inspection based on an image of the wafer in the case in which it is decided that a reference gray level of the image of the wafer is in the predetermined gray level range. 
 
 
 
 
     
     
       7. The wafer defect inspection apparatus according to  claim 6 , wherein:
 the irradiator is configured to irradiate the wafer with the infrared light in a line pattern, 
 the light receiver is an image line sensor, and 
 the controller is further configured to obtain an image of the entire wafer by relatively moving the irradiator, the light receiver, and the wafer mount. 
 
     
     
       8. The wafer defect inspection apparatus according to  claim 7 , wherein the irradiator and the light receiver are disposed on the opposite sides from each other across the wafer mounted on the wafer mount. 
     
     
       9. The wafer defect inspection apparatus according to  claim 6 , wherein the controller is further configured to:
 adjust at least one of an intensity of the infrared light of the irradiator or a photodetective sensitivity of the light receiver and to obtain an image of the wafer again in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range; and 
 modify the exposure time in the case in which the gray level is not in the predetermined gray level range even if the intensity of the infrared light and the photodetective sensitivity of the light receiver are adjusted. 
 
     
     
       10. A wafer defect inspection apparatus comprising:
 a wafer mounting means configured to mount a wafer that is an inspection target; 
 an irradiation means configured to irradiate the wafer with an infrared light; 
 an imaging means configured to image the wafer that has been irradiated with the infrared light; 
 an inspection means configured to inspect a defect of the wafer based on an image of the wafer that has been imaged by the imaging means; 
 a gray level judgment means configured to judge whether or not a reference gray level of an image of the wafer that is the inspection target and that has been imaged by the imaging means is in a predetermined gray level range; and 
 a control means configured to: 
 adjust at least one of an intensity of the infrared light of the irradiation means or a photodetective sensitivity of the imaging means and to obtain an image of the wafer again in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range, and 
 modify an exposure time in imaging the wafer and to obtain an image of the wafer again by the imaging means in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range even if the intensity of the infrared light and the photodetective sensitivity of the imaging means are adjusted, 
 wherein the inspection means is configured to carry out a defect inspection based on an image of the wafer in the case in which it is decided that a reference gray level of the image of the wafer is in the predetermined gray level range. 
 
     
     
       11. The wafer defect inspection apparatus according to  claim 10 , wherein:
 the irradiation means is configured to irradiate the wafer with the infrared light in a line pattern, 
 the imaging means is an image line sensor, and 
 the control means is further configured to obtain an image of the entire wafer by relatively moving the irradiation means, the imaging means, and the wafer mounting means. 
 
     
     
       12. The wafer defect inspection apparatus according to  claim 11 , wherein the irradiation means and the imaging means are disposed on the opposite sides from each other across the wafer mounted on the wafer mounting means. 
     
     
       13. The wafer defect inspection apparatus according to  claim 10 , wherein the control means is further configured to modify the exposure time by changing an image capture rate of the imaging means and modifying a relative velocity of the irradiation means and the imaging means to the wafer mounting means in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range. 
     
     
       14. A method for inspecting a wafer defect comprising:
 irradiating a wafer that is an inspection target with an infrared light by an irradiator and imaging, via a light receiver, the wafer that has been irradiated with the infrared light; 
 judging whether or not a reference gray level of an image of the wafer that is the inspection target and that has been imaged is in a predetermined gray level range; 
 adjusting at least one of an intensity of the infrared light of the irradiator or a photodetective sensitivity of the light receiver and obtaining an image of the wafer again in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range, 
 modifying an exposure time in imaging the wafer and obtaining an image of the wafer again in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range even if the intensity of the infrared light and the photodetective sensitivity of the light receiver are adjusted, and 
 carrying out a defect inspection of the wafer based on an image of the wafer in the case in which it is decided that a reference gray level of the image of the wafer is in the predetermined gray level range. 
 
     
     
       15. A wafer defect inspection apparatus comprising:
 a wafer mount configured to mount a wafer that is an inspection target; 
 an irradiator configured to irradiate the wafer with an infrared light; 
 a light receiver configured to image the wafer that has been irradiated with the infrared light;
 a processor; and 
 a memory that stores an instruction, the apparatus further comprising, as a configuration when the processor executes the instruction stored in the memory:
 an inspector configured to inspect a defect of the wafer based on an image of the wafer that has been imaged by the light receiver; 
 a gray level judger configured to judge whether or not a reference gray level of an image of the wafer that is the inspection target and that has been imaged by the light receiver is in a predetermined gray level range; and 
 a controller configured to:
 adjust at least one of an intensity of the infrared light of the irradiator or a photodetective sensitivity of the light receiver and to obtain an image of the wafer again in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range, and 
 modify an exposure time in imaging the wafer and to obtain an image of the wafer again by the light receiver in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range even if the intensity of the infrared light and the photodetective sensitivity of the light receiver are adjusted, 
 wherein the inspector is configured to carry out a defect inspection based on an image of the wafer in the case in which it is decided that a reference gray level of the image of the wafer is in the predetermined gray level range. 
 
 
 
 
     
     
       16. The wafer defect inspection apparatus according to  claim 15 , wherein:
 the irradiator is configured to irradiate the wafer with the infrared light in a line pattern, 
 the light receiver is an image line sensor, and 
 the controller is further configured to obtain an image of the entire wafer by relatively moving the irradiator, the light receiver, and the wafer mount. 
 
     
     
       17. The wafer defect inspection apparatus according to  claim 16 , wherein the irradiator and the light receiver are disposed on the opposite sides from each other across the wafer mounted on the wafer mount. 
     
     
       18. The wafer defect inspection apparatus according to  claim 15 , wherein the controller is further configured to modify the exposure time by changing an image capture rate of the light receiver and modifying a relative velocity of the irradiator and the light receiver to the wafer mount in the case in which it is decided that a reference gray level of an image of the wafer is not in the predetermined gray level range.